An airbag module for a motor vehicle includes an airbag that may be inflated for restraining a person, at least one outlet opening for releasing gas out of the module and originating at least partially from the inflated airbag, and a reservoir containing coolant for cooling the gas released from the module through the outlet opening. The reservoir includes a wall that sealingly encloses the coolant and is opened to bring the coolant into direct contact with the released gas to cool the released gas.
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1. An airbag module for a motor vehicle, comprising:
an airbag that may be inflated for restraining a person;
at least one outlet opening for releasing gas out of the module which was originally provided by a gas generator for inflating the airbag and which was at least partially contained in the inflated airbag prior to its release through the at least one opening; and
a reservoir containing coolant for cooling the gas released from the module through the outlet opening;
wherein the reservoir comprises a wall that sealingly encloses the coolant and is opened to bring the coolant into direct contact with the released gas to cool the released gas.
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This application is a Continuation of International Application PCT/DE2006/001840, which has an international filing date of Oct. 12, 2006 and was not published in English, but was published in German as WO 2006/131112.
The present invention relates generally to an airbag module for a motor vehicle. The invention relates more specifically to an in airbag module in which outflowing gas is cooled when leaving the module.
An airbag module typically comprises an airbag that may be inflated to aid in restraining a person in a vehicle. The module typically also includes at least one outlet opening through which gas originating at least partially from the inflated airbag is able to be released out of the module. The module also may include and a reservoir with a coolant that is used for cooling the outflowing gas.
In the event of an accident, the airbag may be inflated with gas released from a gas generator and have a high temperature when a hot gas generator is used. The subsequent release of hot gas from the airbag module (in particular from the airbag) may be associated with a risk of injury for people who may come into contact with the gas. Moreover, parts of the vehicle interior fittings may be damaged by hot gas. The gas may be cooled, however the cooled gas generally conducts considerably more easily into an at least partially enclosed space (e.g., the airbag) due to the lower volume of gas required and the airbag may not completely inflate or more gas may be required to inflate the airbag.
One embodiment of the invention relates to an airbag module for a motor vehicle. The air bag module includes an airbag that may be inflated for restraining a person, at least one outlet opening for releasing gas out of the module and originating at least partially from the inflated airbag, and a reservoir containing coolant for cooling the gas released from the module through the outlet opening. The reservoir includes a wall that sealingly encloses the coolant and is opened to bring the coolant into direct contact with the released gas to cool the released gas.
The advantages and features of the invention will become clear from the following Figure descriptions of exemplary embodiments.
European patent application EP 0 620 140 A1, which is herein incorporated by reference in its entirety, discloses an airbag module for conducting gas flowing out of an airbag over steel wool or aluminum wool, for example to cool the gas by heating the metal wool according to one exemplary embodiment.
German patent application DE 196 02 695 C2, which is herein incorporated by reference in its entirety, discloses a gas generator for filling an airbag with gas that may be cooled by direct contact with a liquid according to an exemplary embodiment. A cooling element formed from non-heat-resistant material is filled with a coolant and with foamed silicone rubber. When the hot gas comes into contact with the material of the cooling element, the material is damaged and the coolant released. The foamed silicone rubber may increase the available surface area of the coolant.
Other exemplary embodiments of the invention may allow rapid and effective cooling of gas when releasing the gas from an airbag module even when the gas has been previously used for inflating the airbag.
The released gas from the airbag module may flow to a reservoir which is filled with a coolant. A wall of the reservoir sealingly encloses the coolant on all sides so that a reduced amount of coolant is able to escape from the reservoir provided that the wall of the reservoir is intact and sealed. The wall may be opened in order to allow direct contact between the coolant and the gas to be cooled.
The temperature of the gas flowing out of the airbag may be rapidly reduced by the direct contact of the gas with the coolant and may be efficiently reduced by the relatively low requirement for coolant.
In a preferred exemplary embodiment of the invention, the outlet openings through which the gas is released are located in the gas generator carrier. Alternatively, said outlet openings may be located on the bottom face of the airbag module. A guide plate with a large opening that encloses the outlet openings in the airbag module in a frame-like manner may be fastened to the bottom face. The guide plate may not directly serve as a gas generator carrier but may, for example, be used in a passenger airbag module—similar to the gas generator carrier in a driver airbag module—to guide specific elements of the airbag module (e.g., a valve slide) and to receive openings for releasing gas. The guide plate may also be a device for fastening a pyrotechnic element or thread for fastening further elements to the guide plate. The guide plate is typically attached to the housing of the airbag module.
According to a preferred exemplary embodiment, the coolant reservoir is located in the flow path of the released gas and thus upstream of the outlet openings of the airbag module. Alternatively, the coolant reservoir may be arranged in the flow path of the released gas downstream of the outlet openings of the airbag module.
According to another preferred embodiment, the wall of the coolant reservoir encloses a hollow space or a plurality of hollow spaces, in which the coolant is located. The wall of the coolant reservoir is preferably made from a plastic material.
In another preferred embodiment, the coolant reservoir has a planar basic shape, for example that of a disk-shaped ring or cuboid. The term “planar” is intended to be understood in this case that the expansions of the reservoir are greater in length and width than the expansion in height, while the length and width of the reservoir extend substantially in one plane.
Various exemplary embodiments may include a solid or a liquid coolant. By using various coolants (e.g., water), the cooling of gases may be possible at a wide range of temperatures. As the reservoir only has to be filled with coolant, a more simple and less complicated reservoir may be used.
In a preferred embodiment, the coolant has a sublimation point, evaporation point, or other phase transition point in a temperature range of the gas to be cooled. As a result, direct or indirect contact of the gas to be cooled with the reservoir filled with coolant leads to a higher absorption of energy by the coolant in the course of its phase transition. The high evaporation point, sublimation point or other phase transition enthalpy of the coolant, which is applied to the detriment of the temperature of the gas, leads to an effective cooling of the gas. In comparison with a coolant that has no phase transition in the corresponding temperature range, by utilizing the phase transition enthalpy of the coolant considerably less coolant may be used to achieve a comparable cooling of the airbag gas and increase the efficiency of the cooling process.
The phase transition of the coolant is preferably a transition into the gaseous phase to achieve a volume increase of the coolant that is as large as possible. The alteration to the volume accompanying the phase transition of the coolant may lead to a high increase in pressure inside the reservoir. Preferably, this leads solely, or in combination with the pressure exerted by the outflowing gas on the reservoir and/or with the thermal loading of the reservoir by the hot gas, to an opening of the wall of the reservoir. As a result, coolant is released both in its original state and also in its new state. The direct contact of the gas to be cooled with the released coolant leads to an even more effective energy transmission from the gas to the coolant than was possible by indirect contact as the contact surface area is significantly increased between the gas and the coolant.
According to various exemplary embodiments, the reservoir may not be primarily opened by the internal pressure produced by the evaporating coolant or sublimating coolant, but may be opened by the pressure exerted by the outflowing gas on the reservoir and allow a direct contact between the gas and coolant.
According to other exemplary embodiments, a pyrotechnic unit (which may be separate and associated specifically with the coolant reservoir) is located sealingly on the coolant reservoir. After activation of the pyrotechnic unit by the applied pressure (possibly indirectly via a force transmission element activated by the pyrotechnic unit), an opening is formed in the wall of the coolant reservoir.
Preferably, the wall of the reservoir reacts to overpressure and acts on the wall either from the inside, the outside, in combination with thermal loading by rupturing or splitting open, and/or by a comparable process that damages the wall of the reservoir. The wall may have at least one predetermined rupture point that leads to easier rupture of the wall at that point. The predetermined rupture point may be, for example, a perforation, a score line, and/or a comparable weakened portion.
According to various exemplary embodiments, the outlet openings of the module may be permanently open to allow a continuous outflow of gas from the airbag and/or the module. According to the pressure conditions of the airbag and surroundings and even during the filling of the airbag, one portion of the airbag gas may flow out of the airbag and/or the module and come into contact with the coolant reservoir.
According to other exemplary embodiments, the outflow of gas from the module may be controlled by at least one controllable valve. The control may be carried out by a closure element, for example by a valve slide, as disclosed in DE 103 61 887 A1, which is herein incorporated by reference in its entirety. An annular adjusting disk may be displaced as the closure element in a limited rotational movement by the pressure applied by a pyrotechnic element. In an initial position the outlet openings of the adjusting disk, which may be similar in shape and number to those of the valve main body located above the adjusting disk, are not aligned with said outlet openings of the valve main body and the closure element is closed. By the limited rotational movement, the adjusting disk is moved into a position where the outlet openings are aligned with those of the valve main body and the closure element is open. Such an arrangement may be used when the airbag module is intended to be accommodated in a steering wheel or is intended to have a cylindrical shape. Such a control of the gas flow may, however, also be used when the airbag module is intended to have a generally prismatic or cuboid shape, for example to be used on the passenger side of a vehicle. In this case, an equivalent valve slide carries out a comparable limited translatory movement relative to a guide plate. The energy required for this movement may be provided by a pyrotechnic element in a manner similar to the rotational movement.
According to other exemplary embodiments, the closure element may include projections on the side facing the coolant reservoir. In the defined rotational or translatory movement of the closure element for opening the outflow openings of the airbag module, the projections may come into contact with the wall of the coolant reservoir. This contact may either create a predetermined rupture point in the wall (e.g., in the form of a score or a perforation) or directly tear open the coolant reservoir by damaging the wall. The gas flowing out of the airbag may come even more rapidly into direct contact with the coolant and the time period that the gas requires for flowing out of the airbag module may be shortened.
Alternatively, by the overpressure from inside or outside the wall of the reservoir, an opening device, for example a valve or a flap, is reversibly opened and releases the coolant so that it leads to direct contact between the coolant and the gas. The wall of the coolant reservoir may not be damaged when opening the reservoir but is still intact after closing the opening device.
Preferably, the gas flowing out of the module may flow into a partially or entirely enclosed container. Due to the low temperature of the gas, the gas may have a relatively smaller volume than a gas that has not been cooled. The use of a partially or entirely enclosed container may additionally reduce the risk of injury. Damage to the vehicle interior fittings may also be reduced or eliminated by the lower gas temperature and the use of the container.
In a preferred embodiment, the coolant reservoir is provided with a carrier (for example in the form of a carrier plate) and is attached by fastening elements (e.g., screws) to an airbag device so that the carrier and reservoir are fixedly connected to one another and fixedly connected to a suitable receiving part in the airbag module. The carrier and reservoir may, for example, be fixed between the gas generator carrier and the flange of the gas generator. Both the carrier and the coolant reservoir have circular recesses that are aligned with one another and are generally congruent with the threads in the gas generator carrier into which the screws are fastened. Alternatively or additionally to screwing, the carrier and coolant reservoir may be fastened to the airbag module by clamping, bonding, welding, or similar methods for fastening. The carrier and coolant reservoir may also be connected to one another by clamping, bonding, welding or similar methods for fastening. The carrier may stabilize the coolant reservoir and allow for a larger range of materials from which the coolant reservoir may be made. The carrier itself is preferably produced from a plastic material. The carrier and the coolant reservoir may form a cooling unit as a result of their connection.
The carrier and the coolant reservoir may respectively have a shape such that they may be fitted into differently shaped airbag modules. The carrier and reservoir, for example, may have an annular basic shape to be integrated into an airbag module designed for use in a steering wheel or a similarly shaped housing. The coolant reservoir may, for example, also have the shape of an open ring while the carrier has a general shape of a closed ring with a recess in the region of the opening of the coolant reservoir. These interruptions to the fully closed rings may allow the carrier and coolant reservoir to be incorporated into airbag modules equipped with a pyrotechnic unit for generating pressure for the movement of a valve slide. The carrier plate and coolant reservoir may have a prismatic or cuboid shape and may be incorporated into an airbag module designed for use in a passenger seat in a motor vehicle or for use in any other prismatic or cuboid housing.
When the carrier is arranged between the outlet openings of the gas generator carrier or the valve main body and the coolant reservoir, the released gas from the module flows through the outlet openings of the generator carrier or the valve main body and then through the apertures of the carrier to come into contact with the coolant reservoir. When using a passenger airbag module in which the outlet openings of the module are not in the gas generator carrier but on the bottom face of the airbag module, the same position of the carrier plate and coolant reservoir may result in the released gas from the module flowing out of the airbag and coming into contact with the coolant reservoir first and then flowing through the apertures of the carrier plate and the outlet openings of the airbag module.
Preferably, the carrier has at least one aperture so that the airbag gases are able to escape from the airbag module. The shape and number of apertures are generally similar to the apertures of the outlet openings of the airbag module (e.g., the apertures of the gas generator carrier and/or the valve main body, the apertures of the outlet openings incorporated in the bottom face of the airbag module, etc.). Preferably, the aperture and/or apertures of the carrier are congruent with the outlet opening and/or the outlet openings of the airbag module so that the gas outflow from the module is not hindered by the carrier.
When using a generally cylindrical airbag module, an adapter plate may be fastened to the module by suitable fastening elements, for example screws. The adapter plate may stabilize the coolant reservoir and carrier plate on the respective radial outer faces thereof by clamping. Thus the adapter plate may be an optional component of the cooling unit. The adapter plate may provide and/or allow the incorporation of the airbag module into a steering wheel or a further receiver space in a motor vehicle.
According to one exemplary embodiment, the mode of operation of the cooling of the hot gas when flowing out of the airbag is to be described briefly hereinafter with reference to
A planar carrier plate 31 has the basic shape of a closed ring but has a recess 34 projecting from the outer edge of the plate towards the inside and encompasses less than the complete width of the carrier plate 31 so that the annular basic shape of the carrier plate 31 is not entirely interrupted. The carrier plate 31 and a planar coolant reservoir 32 (with the basic shape of an open ring) are fastened between the gas generator flange 25 and the valve main body 24 by screws 30 such that the carrier plate 31 is located on the side of the valve main body 24 and the coolant reservoir 32 is on the side of the gas generator flange 25. The annular opening of the coolant reservoir 32 is positioned over the recess 34 of the carrier plate 31 so the pyrotechnic element 27 is in contact neither with the carrier plate 31 nor with the coolant reservoir 32. The carrier plate 31 generally has the same number, shape, and arrangement of apertures 33 as the valve main body has outlet openings 26a and the adjusting disk 29 has outlet openings 26b. In
The coolant reservoir 32 has a wall 38 enclosing a hollow space. As in the exemplary embodiments described with reference to
An adapter plate 39 defines a large circular opening with a radius smaller than the external radius of the carrier plate 31 and the coolant reservoir 32. When the adapter plate 39 is fastened with screws 37 in corresponding threads 40 in the module 21, it produces an effective clamping in the radial outer region of the carrier plate 31 and the coolant reservoir 32. The entire airbag module 21 together with integral carrier plate 31 and integral coolant reservoir 32 may be fastened in a steering wheel designed for receiving an airbag module.
The general cooling mechanism of the arrangement shown in
In an exemplary embodiment according to
The carrier plate 57 has a plurality of outlet openings 73, of which one is identified in
The priority application, German patent application no. 202005016457.7, filed Oct. 17, 2005 including the specification, drawings, claims and abstract, is incorporated herein by reference in its entirety.
Given the disclosure of the invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.
Lube, Thomas, Pradel, Andreas, Meissner, Dirk, Heym, Axel, Schliecker, Gudrun
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Mar 15 2008 | SCHLIECKER, GUDRUN | Takata-Petri AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 020833 | /0534 | |
Mar 17 2008 | MEISSNER, DIRK | Takata-Petri AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 020833 | /0534 | |
Mar 17 2008 | PRADEL, ANDREAS | Takata-Petri AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 020833 | /0534 | |
Mar 20 2008 | HEYM, AXEL | Takata-Petri AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 020833 | /0534 | |
Mar 20 2008 | LUBE, THOMAS | Takata-Petri AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 020833 | /0534 | |
Apr 11 2008 | Takata-Petri AG | (assignment on the face of the patent) | / |
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